Intrinsically safe handheld field maintenance tools are known. Such tools are highly useful in the process control and measurement industry to allow operators to conveniently communicate with and/or interrogate field devices in a given process installation. Examples of such process installations include petroleum, pharmaceutical, chemical, pulp and other processing installations. In such installations, the process control and measurement network may include tens or even hundreds of various field devices which periodically require maintenance to ensure that such devices are functioning properly and/or calibrated. Moreover, when one or more errors in the process control and measurement installation is detected, the use of an intrinsically safe hand held field maintenance tool allows technicians to quickly diagnose such errors in the field.
One such device is sold under the trade designation Model 375 Field Communicator available from Fisher-Rosemount Systems, Inc., of Austin, Tex. The Model 375 is an intrinsically safe handheld field maintenance tool that supports communication with field devices of at least two different process communication protocols. In particular, the Model 375 is designed to support HART® and FOUNDATION™ fieldbus devices from many vendors. Moreover, the Model 375 can be used to perform diagnostics for effective startup and trouble shooting of Foundation™ Fieldbus segments. The Model 375 can allow a technician to create a quality segment by diagnosing the network DC voltage and average noise. Moreover, power supply problems can be detected by monitoring low frequency noise on a segment and incorrect terminations and faulty devices can be diagnosed by observing the communications signal level.
In situations where a faulty device is communicating with an appropriate communication signal level, but the communications themselves are erroneous, the diagnostics of prior art handheld field maintenance tools may not suffice. In such cases, relatively larger, and potentially non-intrinsically safe devices such as computers with suitable hardware adaptations are used to essentially capture communication on the process loop in order to allow a technician to diagnose the communication errors. Typically, such computers or control system are located away from the field devices in a control room. Accordingly, if a change is made to a field device in the field, in order to address a communication error, the technician must return to the control room in order to invoke, or otherwise engage, bus monitor functionality in the control system to observe communication of the affected field device.